(a) Field of the Invention
The present invention relates to a system for providing context-aware services and a method thereof.
(b) Description of the Related Art
Various additional services using the Internet are provided as the number of Internet users is increased and Internet services become popular. A Session Initiation Protocol (SIP) is an application layer control and signaling protocol for creating, modifying and terminating sessions with one or more participants. The SIP is widely used in multimedia session control and Internet telephone services.
The SIP supports user mobility by performing a session initiation through a physical contact corresponding to a user identifier (i.e., an SIP identifier) obtained from SIP registration even if a user location is changed to access a communication network or a user uses another service terminal. In further detail, the service terminal of the user transmits an SIP registration message having a contact header including physical contact information corresponding to the user SIP identifier, and an SIP server performs user SIP registration and stores the information in the contact header. Then, when receiving a service request message by the SIP identifier of the user, the SIP server supports the user mobility by transmitting the service request message to the corresponding physical contact.
According to an Internet Engineering Task Force request for comments (IETF RFC) 3840 indicating user agent capabilities in SIP, and capabilities and characteristic information about a user agent carried as parameters of the Contact header field within SIP registration request message. The capabilities and characteristics about a user agent include an ability to generate or process an audio/video service, particular type of message content and available languages and whether or not a user agent is a mobile and so on. In addition, an IETF SIMPLE Working Group suggested a rich presence extension to the presence information data (RPID) format which is a presence data format including information about what the person is doing, the type of place a person is in, the person's mood, the type of service it offers, and the overall role of the presentity.
Accordingly, services have been provided for a corresponding physical contact point by using the SIP registration information and by performing an SIP session negotiation on service terminal capabilities or services based on SIP presence have been provided.
A related approach is a paper entitled “SIP-based Location Aware Services” at “2002 International Conference on Software, Telecommunications and Computer Networks”. In this paper, in order to provide a user location aware service which is one of the context-aware services by using the SIP, a service provider periodically transmits an INVITE request message to a single service terminal in order to obtain the location of service terminal, and provides the service based on geographical location of the service terminal which is obtained from IP address in a response message of the INVITE request message.
Recently, a range of computer usage has expanded from a personal computing area to a ubiquitous computing area as information industry and mobile communication technology have been developed. In the ubiquitous computing service, a terminal senses changes in their environment and automatically adapts and acts based on these changes based on user needs and preferences. Accordingly, services are required to adaptively vary according to a context including a present user location, and a user activity as well as service capabilities of service terminal in a ubiquitous computing environment.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person or ordinary skill in the art.